NAME

       gensio_write - Write data to a gensio

SYNOPSIS

       #include <gensio/gensio.h>

       int gensio_write(struct gensio *io, gensiods *count,
                           const void *buf, gensiods buflen,
                           const char *const *auxdata);

       struct gensio_sg {
           const void *buf;
           gensiods buflen;
       };

       int gensio_write_sg(struct gensio *io, gensiods *count,
                           const struct gensio_sg *sg, gensiods sglen,
                           const char *const *auxdata);

DESCRIPTION

       Write  data  to  the  given  gensio.   The data is in buf and the length of the data is in
       buflen.  Note that gensio_write may not write all of the  data  given,  depending  on  the
       gensio  type  and  the internal buffer space.  It will return the number of bytes actually
       written in count which may be NULL if you don't care.  (Hint:  you  should  almost  always
       care.)

       If  gensio_write  is  unable to write the full amount of data, you should generally buffer
       the unwritten data and call gensio_set_write_callback_enable(3) to know when you can write
       the  rest  of  the  data.   Many  applications always buffer the data and enable the write
       callback to do the write and then disable the write callback when all data is written, for
       consistency.

       gensio_write  will  never block, if it cannot write all the data it will write what it can
       and return.

       auxdata is used to pass in gensio specific auxiliary data, such as the stream  number  for
       SCTP or whether the data is out of band data for SCTP or TCP.

       gensio_write_sg is like gensio_write, but it takes a scatter-gather structure to allow you
       to combine multiple chunks of data without copying.  Note that if you get a partial write,
       you  must  figure out where the write ended in your scatter-gather list and start the next
       write from there.

RETURN VALUES

       Zero is returned on success, or a gensio error on failure.

SEE ALSO

       gensio_err(3), gensio(5)

                                           24 Feb 2019                            gensio_write(3)